Samples are drawn from a Zipf distribution with specified parameter (a),
where a > 1.

The zipf distribution (also known as the zeta
distribution) is a continuous probability distribution that satisfies
Zipf’s law, where the frequency of an item is inversely proportional to
its rank in a frequency table.

Parameters:

a : float

parameter, > 1.

size : {tuple, int}

Output shape. If the given shape is, e.g., (m,n,k), then
m*n*k samples are drawn.